How to remote debug rails app in rubymine 4.5?

There is a short article about how to remote debug a rails app. But it is too brief. Is there a post with details about how to remote debug? Our server is a ubuntu server and development environment is windows. We are looking for answer for the following question:
1. how to set up break point? Is the break point on remote server?
2. What's the $SCRIPT$ in rubymine's edit configuration => ruby remote debug?
3. What's the script needed for remote debug?

Thanks.